There is a communication system for communication between apparatuses via a human body serving as a transmission channel. In this communication system, a pair of electrodes is disposed in an apparatus. One is a signal electrode for transmitting/receiving a signal, and the other is a reference electrode for transmitting a reference potential. Signal electrodes are coupled to each other mainly through human bodies, whereas reference electrodes are coupled to each other mainly through a space and/or the earth ground. With these couplings, the communication apparatus transfers a potential difference between the signal electrode and the reference electrode to the correspondent communication apparatus.
In the above-described communication system, it is preferred that the areas of electrodes be large in order to stabilize coupling between apparatuses. Further, the potential difference becomes small when short circuit between the signal electrode and the reference electrode occurs in the apparatus, and thus the pair of electrodes needs to be spaced apart in the apparatus. Accordingly, when a small radio terminal such as a mobile telephone is made operable as an apparatus for the aforementioned communication system, it is preferred that the pair of electrodes be disposed at both ends of a small radio terminal.
However, an antenna is often disposed in an end portion of a small radio terminal, and it is highly possible that the antenna and an electrode are disposed in the same end portion. Consequently, it is possible that the electrode deteriorates the performance of the antenna.